Only 15 minutes after its closest approach to Pluto on July 14, 2015, NASA’s New Horizons spacecraft looked back toward the sun and captured this near-sunset view of the rugged, icy mountains and flat ice plains extending to Pluto’s horizon. The smooth expanse of the informally named icy plain Sputnik Planum (right) is flanked on the left by rugged mountains up to 11,000 feet (3,500 meters) high, including the informally named Norgay Montes in the foreground and Hillary Montes on the…